There has been proposed an electric power steering for providing steering assist to a driver of a vehicle. In the electric power steering, a motor rotates only when the steering assist is needed. Therefore, the electric power steering has better fuel efficiency than a hydraulic power steering.
Recently, space for accommodating a motor in the electric power steering has been reduced as the number of parts mounted on the vehicle has increased. Further, there has been an increasing demand for the motor to have a fail-safe feature that ensures safety.
In a motor disclosed in JP-2005-328654A, JP-2008-312393A, JP-10-248187A corresponding to U.S. Pat. No. 5,900,687, and JP-2007-330035A, a holder for holding wires of windings of a stator is mounted to an end of the stator in an axial direction, and the wires extend in a circumferential direction inside the holder so that the windings can be electrically connected to a connector that supplies electrical power to the windings.
However, mouthing the holder to the end of the stator in the axial direction can increase the size of the motor in axial and radial directions of the motor. For example, in a conventional brushless motor shown in FIGS. 24A and 24B, a lead wire 101 of a three-phase winding set 100 of a stator is caused to extend in a circumferential direction by a busbar 104 inside a holder 103 that is mounted outside an operation region 102, where the stator is located, in an axial direction. Then, the lead wire 101 is electrically connected to a switching element 106 through a connector 105 of the holder 103 so that the three-phase winding set 100 can be supplied with electric power from the switching element 106. As can be seen from FIGS. 24A and 24B, the size of the motor in axial and radial directions is increased due to the holder 103.
In a motor disclosed in JP-2007-215299A, a wire of each winding is connected to a corresponding switching element.
However, connecting the wire of each winding to the corresponding switching element may increase the number of connection points between the winding and the switching element. Accordingly, wiring of the winding to the switching element may be complicated.